Here’s a new thrombolytic you should know about
A new clot-busting drug, TNKase (tenecteplase), manufactured by South San Francisco, CA-based Genentech, recently was approved by the Food and Drug Administration for treatment of acute myocardial infarction (AMIs).
"The drug is administered more quickly than other thrombolytics, resulting in potential decreased door to-drug times," says Paula Tanabe, RN, PhD, CCRN, advanced practice nurse for the ED at Northwestern Memorial Hospital in Chicago.
Here are factors you need to know about this new drug:
• TNKase is administrated with a single bolus.
TNKase is the first available single-bolus agent, says Tanabe. "The drug can be administered in only five seconds," she reports. (See "It’s time to put TNKase to work" guide to administration, inserted in this issue.)
The single five-second bolus is much faster than the administration of other thrombolytics (90-minute infusion for t-PA, and two boluses 30 minutes apart for r-PA), says Christopher B. Granger, MD, FACC, associate professor of medicine and director of the Cardiac Care Unit at Duke University Medical Center in Durham, NC. "As a single five-second bolus drug, TNKase is easier to administer than t-PA or r-PA," he notes.
The nurse should still have three IV sites, says Sonja D. Brune, RN, MSN, CCRN, CEN, CCNS, critical care/cardiovascular clinical nurse specialist at the Central Cardiovascular Institute of San Antonio. "We use a double-lumen catheter and an 18-gauge saline lock to have three sites with two punctures."
Heparin is administered immediately following TNKase or can be given during the bolus through a separate line, Brune notes.
Not indicated for stroke
• The drug is only approved for AMIs.
Unlike tissue plasminogen activator (t-PA), TNKase is currently not indicated for acute ischemic stroke or massive pulmonary embolism, says Brune.
The indications for use in patients with AMI are the same as with t-PA, says Brune. "These are ST-elevation in two or more contiguous leads, or new bundle branch block with chest pain over 30 minutes from the time of onset," she notes.
• The drug is weight-based.
Dosages of TNKase are patient-specific and should be given according to the patient’s weight, says Brune. "Heparin infusion may be started immediately after flushing the line," she adds. "The monitoring of the patient is the same as with t-PA."
It is always important to weight base your thrombo-lytic as this is thought to decrease the risk of bleeding, Tanabe advises. "All of the other critical care drugs we give in the ED are weight-based. It is just as important with a fibrinolytic," she says.
This especially important for elderly female patients at higher risk for intracranial hemorrhage, says Tanabe. In a subset data analysis, patients over the age of 75 had a 37% less risk of intracranial hemorrhage than with t-PA, she notes.
• The drug has a longer half-life than T-PA.
This characteristic allows for the single bolus administration, says Brune. "It is more fibrin-specific than Retavase [reteplase, manufactured by Centacor], and slightly more fibrin-specific than t-PA," she explains. "This provides action directly on the clot without as much systemic involvement."
• Financial help is available for patients.
The cost of TNKase is the same as t-PA and Retavase (about $2,100), notes Brune. "While this may seem prohibitive, consider that Genentech has a patient assistance program to assist indigent and underinsured patients," she says. (For more information on that program, see resource box, p. 144.)
• The drug requires treatment within 30 minutes.
Shorter time to beginning treatment saves lives, Granger stresses. "Guidelines suggest that patients should have these drugs begun within 30 minutes of presenting," he says.1
You need to have a system in place to assure rapid treatment, and track performance as a quality improvement activity, Granger urges.
• It results in less bleeding.
There is less incidence of nonintracranial bleeding with TNKase than t-PA, says Granger. "This is likely due to its greater degree of fibrin-specificity. That is, it is much more active at the clot itself in the coronary artery and causes less disturbance of the coagulation system." (See story on risks of TNKase, below.)
This preserves the body’s ability to form new blood clots as necessary to prevent new bleeding, Granger explains. "This is especially important in patients at higher risk of bleeding, such as patients with lower body weight, females, and the elderly," he says.
Reference
1. Ryan TJ, Antman EM, Brooks NH, et al. 1999 update: ACC/AHA guidelines for the management of patients with acute myocardial infarction: A report of the American College of Cardiology/American Heart Association task force on practice guidelines (committee on management of acute myocardial infarction). J Am Coll Cardiol 1999; 34:890-911.
For more information on TNKase, contact:
• Sonja D. Brune, RN, MSN, CCRN, CEN, CCNS, Central Cardiovascular Institute of San Antonio, 927 McCullough Ave., San Antonio, TX 78215. Telephone: (210) 271-3203. Fax: (210) 223-9600. E-mail: [email protected].
• Christopher B. Granger, MD, FACC, Duke Clinical Research Institute, 2400 Pratt St., Room 0311, Terrace Level, Durham, NC 27705. Telephone: (919) 668-8900. Fax: (919) 668-7056. E-mail: [email protected].
• Paula Tanabe, RN, PhD, CCRN, Emergency Department, Northwestern Memorial Hospital, 251 E. Huron, Feinberg Pavillion, Mezzanine 714, Chicago, IL 60611. Telephone: (312) 926-8249. Fax: (312) 926-6288. E-mail: pmt35@ pcc.net.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content